1. Field of the Invention
The present invention relates to an optical device for varying an optical performance of a passing light beam by varying a relative angle of a pair of transparent parallel-plane plate having an optically transparent material filled therein, and that is suitable for use in an image stabilizing optical device, which is arranged in an imaging system of a photographic camera or a video camera to compensate for a vibration of an image due to a vibration of the imaging system.
2. Related Background Art
An optical device in which an optically transparent material, such as a liquid or a silicon rubber, is filled between a pair of transparent parallel-plane plates to form a variable apex angle prism, where an angle (parallelism) between the pair of parallel-plane plates is varied by an external drive force to vary an optical performance of a passing light beam has been proposed in the art.
FIG. 5 shows a known optical device.
The optical device shown in FIG. 5 has two transparent parallel-plane plates 201 arranged to face each other.
The pair of parallel-plane plates 201 are supported by a ring-shaped support member 204 having an L-shaped cross-section. Peripheries of the parallel-plane plates 201 are held by a flexible ring-shaped connecting member 202 which is thermal-bonded to the support member 204, and a transparent material 203 such as silicon rubber or liquid is filled therein.
The optical device forms a variable apex angle prism whose apex angle is variable by varying the angle between the two parallel-plane plates 201 by the drive force from the external drive means 205, to deflect an incident light beam h by a desired angle.
In the prior art optical device, a material which is easily thermal-bonded to the connecting member such as a relatively soft material is selected as the support member, and the drive force is applied to the support member to vary the apex angle of the prism formed by the two parallel-plane plates.
As a result, a response of inclination of the parallel-plane plates when the drive force is applied to the support member by the drive means is slow, and it is difficult to quickly vary the apex angle of the variable apex angle prism formed by the pair of parallel-plane prism. Accordingly, the tracking ability to stabilize the image against the vibration of the camera is poor.